The invention relates to a biopsy needle especially suited for use in a so-called biopsy gun, as well as a biopsy system.
Biopsy needles according to the species are generally known. Mention is made of DE-A-39,24,291 merely as an example, to which reference is expressly made otherwise to explain all terms not presented here in greater detail.
Known biopsy needles have at least one inner needle (mandrel) and an outer tube (also called a cannula). The mandrel has a recess (notch) located in the vicinity of its distal end, provided with a point, said notch receiving the tissue sample to be collected and having at its proximal end a first connecting element for connection with a slide of the biopsy gun. The outer tube or cannula is displaceably guided on the inner needle, and is likewise provided at its proximal end with (a second) connecting element for connection with another slide of the biopsy gun. The connecting elements in known biopsy needles are designed as flanges that cooperate with matching contact surfaces on the slides.
The biopsy needle described in DE-A-39,24,291 is shown in FIGS. 1a-1d and 2.
The inserting unit illustrated in FIGS. 1 and 2 serves to insert biopsy cannulae and includes three slide elements 1 to 3 which are supported in a housing 4 for displacement along a common axis 5. In order to reduce the illustration to the essentials, merely one pin element 6 is shown as one example of the supporting elements on which the slide 1 is supported for displacement along the extension of the axis 5.
Compression springs 7 to 9 are provided to drive the various slides, whereof spring 7 is inserted between the casing 4 and the rear face of the slide 2, while spring 8 is located between a stop 10 at the slide 1 and the bearing surface 2' at the slide 2, whereas spring 9 is clamped between another stop 11 at the slide 1 and the slide 3.
Moreover, pawIs 12 to 14 are provided as trigger elements whereof pawl 12 is supported at the casing while the pawIs 13 and 14 are provided at the slide 2. The pawIs 12 and 14 engage into associated recesses at the slides 2 or 3, respectively, while the pawl 13 bears against the stop 10 of the slide 1.
FIG. 2 illustrates the attachment of a biopsy needle 21 at the slide 2 and of an exterior tube 22 of a biopsy cannula at the slide 3. FIG. 2 shows the provision of a positive connection as an example of the interconnection between the elements 21 and 22 of the biopsy cannula, on the one hand, and the slide elements 2 and 3, on the other hand.
In the initial condition prior to the initiation of the inserting procedure, which is illustrated in FIG. 1a, the compression springs 7 to 8 are biased while the slide elements 1 to 3 are each arrested by the associated pawls or triggering elements 12 to 14. The cannula is retracted accordingly, with the exterior tube 22 covering the cavity in the biopsy needle 21.
The sampling operation is started by actuation of the pawIs or triggering elements 12. This action causes the slides 1 to 3 to be jointly displaced by the spring 7 along the axis 5. A stop 41 at the casing 4 limits the distance by which the three slides may be displaced.
FIG. 1b illustrates the condition of the inserting unit after insertion of the biopsy cannula. As a result of the joint movement of the individual cannula elements, the exterior tube 22 remains in a position pushed over the needle 21 so far that the cavity in the needle 22 is covered.
With the elements in this position, it is now possible to actuate the trigger element 14 either automatically under control of appropriate actuator elements such as a (non-illustrated) cam guide at the casing 4 or manually. This operation initiates the movement of the slide 3 under the action of the spring 9 toward the stop 10. FIG. 1c shows the result of this movement for the inserting unit. Retraction of the exterior tube 22 into a position behind the cavity in the biopsy needle is caused by the movement of the slide element 3 relative to the slides 1 and 2.
Then the triggering element 13 is actuated equally automatically, e.g., by means of an appropriate cam guide, or by hand. This action causes the spring 8 to displace the slide 1 together with the slide 3 fixed to it in a direction toward the stop 41 while the slide 2 remains stationary (FIG. 1d). As a result of this movement, the exterior tube 22 is pushed again over the cavity in the needle 21. The advancing movement of the exterior tube 22 separates that part of the tissue from the remaining tissue which has bulged into the cavity due to the elasticity of the tissue, such that a small tissue sample is retained in the cavity, which may then be removed, e.g., by a suitable rearward movement of the inserting unit, with the biopsy cannula following as one unit consisting of the needle 21 and the exterior tube 22.
Known biopsy needles have the disadvantage that under certain conditions it may be difficult to insert the biopsy needle into the biopsy gun under sterile conditions. In known biopsy needles, the mandrel is freely displaceable in the cannula; on the other hand, the two slides of the biopsy gun, with which the connecting elements provided on the mandrel and the cannula must be connected, have a certain spacing that depends upon the state of the biopsy gun (cocked or not cocked). It may therefore be necessary, prior to inserting the biopsy needle, to align the latter relative to the relative position of the mandrel and cannula. In addition, under certain conditions the flange connection does not prevent individual elements from slipping relative to the slide.